Information provided by Intel in its own presentations about its upcoming mainstream LGA1155 Sandy Bridge CPUs appears to confirm the company has designed the CPUs to deliberately limit overclocking.

A video leaked to HKEPC and posted on YouTube (see from 2mins onwards) confirms the fact that only a 2-3 per cent OC via Base Clock adjustments will be possible. This is because Intel has tied the speed of every bus (USB, SATA, PCI, PCI-E, CPU cores, Uncore, memory etc) to a single internal clock generator issuing the basic 100MHz Base Clock.

If the problem is simply there is a master clock signal, it doesn't seem like it would be impossible to intercept the clock signal to the CPU with a second clock gen+controll chip integrated into the mainboard, and run that one off a ratio to the master clock generator allowing the CPU to be controlled?

Better question, there are two types of Sandy Bridge sockets, and hence two different types of chipset platforms. Instead of 1156/1366 it will be 1155/2011 sockets/platforms. No one has confirmed this affects SandyBridge B2 (Socket R) or matching chipset.

Socket R SB chips retain the QPI link, therefore I suspect it will overclock just like current 1366 chips do.